I used to have an Element. Great vehicle! The dealer is partially right...to remove the washer fluid tank, you do have to remove the front end of the vehicle (the big piece around the headlights, grille, and front bumper). But it is SO EASY to do on an Element! With a flat-blade screwdriver and a socket wrench, it is possible to have that entire piece off in 10-15 minutes. No I'm not kidding...I did it twice when I had my Element...once to install foglights, and again to install a louder horn.
Open the hood, and look at the plastic cover over the radiator. See those little things that look like black plastic rivets? A bunch of those and either 2 or 4 bolts hold the entire front clip in place. Take the flat-blade screwdriver, put it in the notch conveniently provided on those clips, push the tip of the screwdriver under the center section of the clip, and gently twist the screwdriver till the center section of the clip pops up. You can now remove that clip. There are several of those by the radiator that would need to be removed (maybe 5-10 of them), and about another 5-10 on the underside of the front end...stick your head under the front bumper and you'll see them. The socket can be used to remove the small bolts that are at the leading edge of the front wheel well...there's either one or two per side. The entire front end will come off once you've removed all the clips and those little bolts. The front end is very light and easily moved by one person. For re-installation I'd recommend two people though...a second set of hands will help when trying to line up the front end around the wheel wells.
The washer fluid bottle is on the passenger side, up in front of the front wheel. Remove it, clean it with your choice of cleaner, reinstall it, put your front end back on, and you're done. One hour maximum.
For more info on Elements, go to www.elementownersclub.com and look around the forums there. GREAT bunch of Element enthusiasts there who can answer pretty much any question about the E that you might have.